Hydatid hepatic cyst rupture into bile duct is a complication of hydatid disease. The rupture is more frequent in right or left epatic duct and occasionally in common bile duct (7-9%). A 50-year old man came to emergency room owing to jaundice, fever and abdominal pain. TC show an hydatid cyst with daughter's cyst of left liver and dilatation of biliary tree. Laboratory data of significance included an increased of liver function tests (Bilirubin, Alkaline ph., SGOT, SGPT), VES and leukocytosis. The patients was surgically treated, by total pericystectomy, colecystectomy and coledocotomy with lavage o common bile duct; finally we placed one Kehr drainage and two abdominal drainage. After 15 days of postoperative hospitalization patient was discharged. The best treatment of hydatid cyst is total pericystectomy (when possible). An alternative surgical treatment is possible for the presence of communication with biliary tree. ERCP is very important for a correct diagnosis and for a complete surgical treatment.